Microsoft has unveiled its latest weapons in the war of mobile computing, the Surface Pro 4 and the Surface Book.

The Surface Pro 4 is a tablet with keyboard attachment while the Surface Book is a laptop with detachable keyboard. Yup, they do sound like the same thing coming from different angles.

But Microsoft is insistent they are different and will appeal to different people.

We dug a little deeper to see just how different they really are.

While the Surface Pro 4 is Microsoft's most powerful tablet yet, offering twice the speed of a MacBook Air apparently, it's still got nothing on the Surface Book. The Surface Book is aimed at all out power users. It, Microsoft says, is faster than Apple's MacBook Pro.

Both devices feature the latest sixth-generation Intel Core processors with both i5 and i7 options. But it's the Surface Book that goes to the next level with its optional GPU. The standard model features an Intel Core i5 with HD graphics 520. But this can be upgraded to an i5 or i7 with an Nvidia GeForce GPU that uses GDDR5 memory.

Both models offer various storage options. While only the Surface Pro 4 starts at 64GB, both have 128, 256, 512GB and 1TB SDD variants available. Both are also able to support up to 16GB of RAM.

The Surface Pro 4 is 8.4mm thick while the Surface Book is just 7.7mm thick, according to Microsoft. An impressive feat considering the amount of power crammed into the device - that larger screen must allow it all to be spread a little thinner.

Bigger isn't always better when it comes to being mobile. But with a 12-hour battery life the Surface Book still manages to stay mobile with a larger screen.

The Surface Book features a 13.5-inch display with 3000 x 2000 pixel resolution for 267ppi. This is in a 3:2 aspect ratio and uses Microsoft's PixelSense Display tech.

The Surface Pro 4 also has a PixelSense screen, meaning the world's thinnest Gorilla Glass 4 screen. It is a 12.3-inch display with 5 million pixel which is a 2736 x 1824 resolution screen.

So both displays offer super clear, high- resolution 267ppi screens, but one is larger than the other. So this may come down to the needs of the user, not that the size variation is even that great.

Since the Surface Pro 4 is primarily a tablet the Type Cover is still about being a case as well as a keyboard. This has been improved and features backlit keys, a larger trackpad with 5-points of sensitivity.

But the Surface Book features a fully fledged keyboard that Microsoft describes as "quiet, stable and comfortable". It says this offers best-in-class keystroke. It also features a trackpad with 10-points of sensitivity.

Both feature the Surface Pen with its 1,024 points of sensitivity. Combined with those PixelSense displays this is meant to work better than ever. This is stored magnetically and offers a full year of use with its battery.

The Surface Pro 4 and the Surface Book feature USB 3.0, but the Surface Book has two ports where the Surface Pro 4 only has the one.

Both also feature Mini DisplayPort, microSD, stereo headphone and a power connector.

Each of the machines run full Windows 10 meaning Continuum support for use across Windows 10 devices.

The Microsoft Surface Pro 4 will start at £749 when it's released on 26 October. This model will feature an Intel Core i5 processor, 4GB of RAM and a 128GB SSD. The top end is a Core i7 with 16GB of RAM and 1TB SSD.

The Microsoft Surface Book will start at $1,499, which is about £985, for an Intel Core i5 with 8GB of RAM. The highest end Intel Core i7 with 16 GB of RAM goes for $2,699 which is about £1,775.

READ: Microsoft Surface Book: Everything you need to know about the world's fastest laptop